1. Field of the Invention
The present invention relates to a metering device and more particularly to such a metering device which is adapted to serve both as a receptacle for fluid to be metered and as a timing device for determination of the time required to meter the fluid therefrom, the device having particular utility for use in model aircraft employed in competition wherein it is important precisely to control the time of engine operation while reducing to an absolute minimum the total weight of the aircraft.
2. Description of the Prior Art
There are a variety of circumstances in which it is important to meter minute quantities of fluid and to be able to determine with precision at any given moment how much time will be required to meter the fluid remaining to be metered. In hospitals, for example, it is often important to dispense minute quantities of medication into fluids which are fed intravenously to a patient. In these circumstances not only the time but the quantity of the fluid metered is important in caring for the patient. Heretofore, gravity feed devices or syringes have been employed for this purpose. Such devices are notoriously cumbersome, imprecise and subject to failure.
Another quite different environment in which the metering of minute quantities of fluid is required is in model aircraft which utilize small bore engines. In certain types of competition, the length of time that the model aircraft remains airborne after a given period of engine operation is used in determining the winner. In such competition, engine operation beyond the prescribed time period disqualifies the competitor while engine operation short of the time period severely handicaps the competitor. Thus, in this type of competition as well as in all model aircraft operation, it is important to control the precise time of engine operation. Prior art devices employed in model aircraft to provide this control primarily related to mechanical timing devices which shut off the supply of fuel to the engine upon the passage of the selected time interval. Such devices are imprecise, subject to breakdown and of a weight which detracts from the flight characteristics of the aircraft.
Therefore, it has long been known that it would be desirable to have a metering device which permits the dependably precise metering of minute quantities of fluid therefrom, which is not dependent upon gravity feed, external pressure, or mechanical operation and which is of minimal weight providing an unparalleled dependability of operation throughout a long operational life.